Catalytic reforming of petroleum hydrocarbons with platinum on a low benzene chemisorption alumina



June 27, 1967 LAWRANCE 3,328,285

CATALYTIC REFORMING OF PETROLEUM HYDROCARBONS WITH PLATINUM ON A LOW BENZENE CHEMISORPTION ALUMINA Filed July 8 1964 4 Sheets-Sheet 1 E C M R m WL mm V0 EH Wm A 7 1% IMP 7 W,

MORGAN, FINNEGAN, DURHAM 8: PINE ATTORNEYS June 27, 3967 W E 3,328,2 6

CATALYTIC REFORMING 0F PETROLEUM HYDROCARBONS WITH PLATINUM ON A Low BENZENE CHEMISORPTION ALUMINA Filed July 8, 1964 4 Sheets-Sheet 2 INVENTOR, PAUL ANTHONY LAWRANCE MORGAN, FBNNEGAN, DURHAM 8a PINE ATTORNEYS 3,32%6 WITH 4 \\& \\\\\\Y w w w 4 Sheets-$heet S P. A. LAWRANCE ING OF PETROLEUM HYDROCARBONS LOW BENZENE CHEMISORPTION ALUMINA CATALYTIC REFORM PLATINUM ON A Filed July 8, 1964 6 Md f/Wfffl 401/14 AM/Afif/Mfl INVENTOR. PAUL ANTHONY LAWRANCE MORGAN, FINNEGANV DURHAM & PENE ATTORNEYS June 27, 1967 P. A. LAWRANCE 3,328,286

CATALYTIC REFORMING OF PETROLEUM HYDROCARBONS WITH PLATINUM ON A LOW BENZENE CHEMISORPTION ALUMINA Filed July 8, 1964 4 Sheets-Sheet 4 [/6522 if! Q g 2} 0% N 544 ii //i f/Y/Zf/V flZ/fl/lf lid/AX? ZZZ/71? 2 f y w \J E w y; M Q

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INVENTOR, PAUL ANTHONY LAWRANCE MORGAN,FINNEGAN, DURHAM 8| PINE ATTORNEYS United States Patent 3,328,286 CATALYTIC REFORMING 0F PETROLEUM HY- DRGCARBONS WITH PLATINUM ()N A LOW BENZENE CEEMISORPTHON ALUMWA Paul Anthony Lawrance, Sunhury-on-Thames, Middlesex, England, assignor to The British Petroleum Company, London, England, a corporation of England Filed July 8, 1964, Ser. No. 381,036 Claims priority, application Great Britain, Aug. 2, 1963, 30,671/63; Feb. 27, 1%4, 8,185/64 19 Claims. (Cl. 20865) This invention relates to the catalytic reforming of hydrocarbons using a platinum group metal-alumina catalyst.

Catalytic reforming using a platinum-alumina catalyst is a well-established petroleum conversion process which is used to upgrade gasoline and naphtha boiling range hydrocarbons (i.e. C to 204 C. fractions) to products of increased aromatic content. These products can be used either as high octane gasolines or as sources of aromatics.

A variety of aluminas have been proposed as supports for the platinum group metal but the predominant emphasis has been on aluminas which show appreciable catalytic activity in themselves, particularly hydrocracking activity. Hydrocracking activity is, in its turn, related to the acidity of the aluminas and consequently the normal commercial catalysts have a moderate to high acidity. The emphasis on catalysts with hydrocracking activity is believed to stem from a desire to achieve high octane numbers at moderate temperatures. An alternative approach, however, is to rate a catalyst in terms of the yield of product obtained for a given octane number. Thus, the present invention is concerned with the use of a catalyst which gives products with an improved yield-octane number relationship.

There is accordingly disclosed a process for the catalytic reforming of hydrocarbons which comprises contacting a gasoline or naphtha in the presence of hydrogen and under reforming conditions, with a catalyst of a platinum group metal on a support consisting of an alumina having a reversible benzene chemisorption, as hereinafter spe cified, of up to 5 ,umols/ g.

The invention further consists in a process for the catalytic reforming of hydrocarbons which comprises contacting a gasoline or naphtha in the presence of hydrogen and under reforming conditions, first with a catalyst of a platinum group metal on a support consisting of an alumina having a reversible benzene chemisorption of up to 5 ,umols./g., and then with a catalyst of a platinum group metal on a support which is more acidic than the-aforementioned alumina.

Preferably the reversible benzene chemisorption is at least 0.3 ,umole/ g.

The reversible benzene chemisorption is a measure of acidity, low figures indicating a low acidity. The measurement of the benzene chemisorption of an alumina involves contacting the alumina with benzene vapor at a low partial pressure and a fixed temperature, and measuring the amount of vapor adsorbed and desorbed. The amount of the benzene chemisorbed may vary with the test conditions used, and in particular with the partial pressure of the benzene vapor and the temperature. It is thus necessary to standardize the conditions, and for the purpose of the present invention the partial pressure used is 0.1 mm. Hg, and the temperature 193 C.

One description of a suitable technique for measurement of benzene adsorption and an apparatus therefor is to be found in a paper by R. C. Pitkethly and A. G. Goble, entitled The Adsorption of Benzene on Supported Platinum Catalysts, and published in Actes due Deuxieme Congres International de Catalyse, Paris, 1960, vol. 2, at

amazes Patented June 2?, 1067 (a) A vapor introduction device; (b) A holder for the solid to be tested; (c) A vapor detector.

The vapor introduction device has a source of carrier gas, for example nitrogen or hydrogen, a container for the material to be adsorbed and a valve allowing either the gas alone or gas containing very small quantities of the material to be adsorbed to pass over the solid. The holder which contains the catalyst or catalyst support is capable of being held at a constant temperature over a Wide temperature range. Gas passing over the catalyst then goes via the sampling valve to the vapor detector which may be a hydrogen flame-ionization detector. The detector system may have gas chromatographic columns if the relative rates of adsorption of dilferent materials are to be determined or if reaction is likely under the conditions of test and the composition of the reaction product is to be determined. This is not likely to apply to the present invention.

By passing a stream of gas containing material to be adsorbed over the catalyst or catalyst base to be tested and measuring the difference between the amount of material fed to the catalyst or catalyst base and the amount passing to the detector, the amount of material adsorbed can be determined, after a small correction for dead space in the system. If the fiow of material is then discontinued and gas alone is passed over the catalyst, the amount of material which can be desorbed can also be determined. The amount desorbed is known as the reversible adsorption; the difference between the amounts adsorbed and desorbed is known as the irreversible adsorption.

The carrier gas for the benzene vapor should be inert to alumina and is, preferably, nitrogen.

The aluminas to be tested are desirably given a standard pretreatment to bring them to a standard chemical and physical state and eliminate any effects which could be due, for example, to different water contents. Prolonged heating in an inert atmosphere is preferred, for example heating between 100-800 C. in dry nitrogen for from 1 to hours. A particularly preferred pretreatment is heating at 500 C. for 16 hours in dry nitrogen.

Preferably the test is carried out on aluminas alone. However since the catalysts also contain a platinum group metal it may be convenient or necessary, in certain circumstances, to carry out the test on aluminas which a1- ready have a platinum group metal composited therewith. If a platinum group metal is present, this will also adsorb the benzene. However this platinum group metal adsorption is irreversible, and can, therefore, be distinguished from the reversible adsorption due to the alumina.

Aluminas having a reversible benzene chemisorption of up to 5 ,umols/ g. are hereinafter termed low-acidity aluminas. They may suitably be prepared from the alumina hydrate known generally as pseudoboehmite. This hydrate is characterized by a poorly crystalline form showing a diffuse boehmite type X-ray diffraction pattern. On calcination under normal conditions (e.g., temperatures of 450-650 C.) the hydrate is converted to a poorly crystalline alumina which some authorities refer to as gamma-alumina and some as etaalumina. The second nomenclature is preferred and will be used in describing the present invention.

The aluminas used should be of high purity, having in particular an alkali metal content of less than 0.01% wt., and a preferred method of preparation is to form pseudoboehmite by hydrolyzing an iluminium alcoholate at less than 70 C. under conditions such that the normal crystallization sequence amorphous-9 pseudoboehmite bayerite does not proceed beyond the pseudobohemite stage. A particularly suitable hydrolyzing medium is an aqueous solution of hydrogen peroxide. The concentration of hydrogen peroxide may conveniently be in the range 13 wt., increase in the concentration under otherwise similar conditions, tending to decrease the degree of crystallinity of the pseudoboehmite. The hydrolyzing temperature may be within the range 0 C. to 70C., preferably from 0 C. to 40 C.

The aluminium alcoholate may be prepared in any convenient manner. One suitable method comprises reacting aluminium metal with an alcohol, preferably in the presence of a small quantity of mercury or of a mercury compound. A preferred alcoholate is aluminium isopropoxide.

The aluminium alcoholate may, if desired, be dissolved in a hydrocarbon solvent, which may be a pure hydrocarbon, for example an aromatic hydrocarbon, such as benzene or toluene, or a paraffinic or cycloparafiinic hydrocarbon, or the solvent may be a mixture of hydrocarbons, for example a petroleum fraction boiling in the gasoline or naphtha range (i.e., up to 204 C.). Preferably the solvent has an appreciably greater solvent power for the alcohol produced by the hydrolysis than the water used as hydrolyzing medium, thereby facilitating the recovery or re-use of the alcohol. The presence of the hydrocarbon solvent appears to facilitate the reaction between the alcoholate and water.

After the hydrolysis the hydrated alumina is separated from the other materials present. The hydrocarbon solvent, if used, will contain some of the liberated alcohol and this may be decanted. The aqueous phase may be separated by filtering and washed as necessary.

No ageing of the wet hydrated alumina is necessary. However, if it is not possible to carry out the next step of catalyst preparation immediately (i.e., if there is unavoidable ageing) this will not be deleterious, since a particular feature of the pseudoboehmite hydrogels used in the present invention is their stability.

The wet alumina hydrate may be dried at, for example 100-110 C. and calcined to alumina under normal conditions (i.e., temperatures of 250 to 650 C., preferably 250 to 550 C.).

The preferred platinum group metal is platinum and the platinum group metal may be added by known techniques at any convenient point in the alumina preparation. Preferably it is added to the wet alumina hydrate and for this purpose the alumina hydrate filter cake may be redispersed as a slurry and a platinum group metal compound added. The platinum group metal compound composited with the hydrated alumina is preferably a platinum group metal sulphide and a particularly preferred method of forming this is to add a solution of a platinum group metal compound, for example chloroplatinic acid, to the hydrogel and to precipitate platinum sulphide by the addition of hydrogen sulphide in, for example, the form of a saturated aqueous solution. The amount of platinum group metal composited with the hydrated alumina should be sufficient to give a finished catalyst containing from 0.01 to wt., preferably from 0.1 to 1% wt., of platinum group metal. The platinum group metal-alumina hydrate composite may then be filtered, and dried and calcined as indicated above.

The benzenechemisorption technique used to determine the suitability of aluminas for use in the present invention is illustrated with reference to the accompanying drawings, in which:

FIGURE 1 is a diagrammatic flow sheet of an apparatus for measuring benzene chemisorption, and

FIGURE 2 is a typical record obtained with the apparatus of FIGURE 1.

In FIGURE 1, nitrogen from a source 1 is passed through a pressure regulator 2, controlled with reference to a'pressure gauge 3, to impurity traps 4 and 5 containing,

respectively, manganous oxide to remove oxygen and a 4 A molecular sieve to remove water. After the traps the nitrogen line is split, one branch 6, having a valve 7 in it, passing to the vapor diffusion device 8. This device has a sintered disc 9 at the end of line 6 to give a turbulent nitrogen flow, an inner container 10 which is a constant base capillary tube, containing the material to be adsorbed, and a water jacket 11 controlled by a thermostat (not shown) to give a constant temperature which also controls the amount taken up by the nitrogen. Line 12 connects the diffusion device 8 with a selector valve 13. Also connected to the selector valve is a line 14 having a Valve 15, which by-passes vapor diffusion device 8 and a line 16 with associated pressure gauge 17 and valve 18 through which pure hydrogen may be fed. This line 16 is only required if the system has to be purged or if hydrogen is required as a pretreatment or carrier gas.

From selector valve 13 a line 19 passes to the sample holder 20, which is a stainless steel tube 2% inches long and inch bore, the sample to be tested being held in the tube by quartz wool plugs. A furnace 21 surrounds the holder 20, heated by an electrical winding (not shown). The temperature of the furnace is controlled by a thermostat and thermocouple, the lead of which is shown at 22. From the holder 20 a line 23 passes via a union 38 to a sampling valve 24 and a line 25 from the valve 24 allows gas to flow to atmosphere through a soap film flowmeter 26. A line 27 from the selector valve 13 which by-passes the sample holder 20 can also be connected via union 38 to the sampling valve 24. A line 28 leads from the valve 24 1 to the hydrogen-flame ionization detector 29. The sampling valve can be operated at regular intervals by a pneumatic cylinder 30 which is in turn activated by a solenoid 31 and a timer 32.

The hydrogen flame-ionization detector is of a known type as described in Gas Chromatography, Third Symposium (Ed. R. P. W. Scott), Butterworth and Co. at page 46. It consists essentially of a source of hydrogen 33 and air 34 giving a hydrogen flame at 35. Gas from the sampling valve 24 is fed via line 28 to the hydrogen flame and changes in the ionization of the surrounding atmosphere are recorded electrically, amplified at 36, and used to actuate a pen recorder 37.

In operation a sample of catalyst is placed in the sample holder 20. Selector valve 13 is manually positioned so that nitrogen line 14 is connected to the holder 20, the nitrogen passing over the catalyst through line 23 to the atmosphere. The furnace 21 is brought up to the desired pretreatment temperature and held for a given period while nitrogen flow is continued. This constitutes the conditioning pretreatment. During this time nitrogen and vapor from line 6 are passing through the selector valve 13 via the by-pass line 27 through the union 38 to the sampling valve 24. Operation of the valve timing device is started so that, at regular intervals, samples of the nitrogen and vapor pass to the detector 29. This enables the composition of the nitrogen feed stream to be determined and adjustment made to the flow valve 7 to give the desired partial pressure of vapor in the nitrogen.

At the end of the conditioning period, and providing the vapor partial pressure is constant, the furnace temperature is adjusted as necessary. When a steady tem 27 is disconnected from the union 38 and line 23 con- 1 nected in its place. The selector valve 13 is then manually operated so as to direct nitrogen and vapor to the holder 20. At the same moment the sampling valve 24 is restarted and samples of the effluent are automatically taken at regular intervals and the detector response, which is a measure of the vapor concentration in the efiiuent, is recorded. This will be less than the amount fed according to the amount adsorbed on the catalyst and the flow is continued until no more vapor is adsorbed, i.e. the composition of the feed and effluent are the same. Selector valve 13 is then altered again so that pure nitrogen free of vapor is directed into the holder. Adsorbed vapor is desorbed from the catalyst and recorded in the effluent. When no further vapor is desorbed the test is terminated.

A typical record of a test is shown in FIGURE 2. During the period when nitrogen and vapor are passing, the detector shows initially no response indicating that all the vapor is being adsorbed and none is appearing in the efiluent. Vapor gradually appears in the efliuent until it reaches a steady state, the amount being recorded at regular intervals. Nitrogen alone is then passed and the amount of vapor desorbed is recorded until the effiuent composition is steady. From such a record a quantitative determination of the amount of vapor adsorbed and desorbed can be made. Thus, after a correction for the known dead volume of the apparatus, the amount adsorbed is the difference between the total rectangular area of the adsorption period and the area under the curve formed by the peaks of the regular periodic records. The amount desorbed is the area under the curve formed by the peaks during the desorption section of the record. A quantitative figure for the actual mass of vapor passed during the adsorption period can be obtained from the vapor diffusion device 8, either by direct measurement of the small change of liquid level in the inner container during the adsorption using a travelling microscope, or by calculation according to the formula in P p S- --maSSt1'anSfer (g- SCC.

DIVIPA S- RTZ where This gives a correlation between the actual area of the record and the mass of vapor passed and enables the areas to be converted into quantitative figures. The amount desorbed is the reversible adsorption, which can be expressed in umoles/gram of catalyst.

The apparatus and the technique naturally require considerable attention to detail and accuracy in accordance with known analytical procedures beyond the brief details given above. Once the apparatus and techniques have been established, however, the method is rapid and accurate and capable of being used on relatively small samples.

In addition to the discovery that an improved yieldoctane number relationship is obtained by the use of a platinum group metal on a low-acidity alumina support, it has been found that the reforming process may be still further improved by the use in combination of such a catalyst and a second catalyst having a platinum group metal disposed on a more acidic support. Catalysts of a platinum group metal on an acidic alumina support are well known in the art, and the acidic alumina may be derived from alumina hydrate precursors which contain predominantly trihydrate aluminas, particularly betaalumina trihydrate (also known as bayerite).

Where, as is preferred, the acidity of the second catalyst support is conferred by the nature of the alumina itself, a convenient criterion of acidity may be a reversible benzene chemisorption of at least 10 ,umols/g, and preferably at least ,umols/ g.

Alternatively, acidity may be conferred on the alumina by the addition of halogens, particularly fluorine and chlorine, to the catalyst during its preparation and/ or to the reforming reaction zone or zones. Thus, halogen injection may be made to the feed stream just prior to contact with the more acidic catalyst. The halogen may be present in an amount of from 0.1 to 8% wt. by weight of the total (second) catalyst, particularly 0.1 to 2% wt. However if a halogen-containing catalyst is used, care should be taken to ensure that excessive halogen does not enter the reaction zone or zones containing the low-acidity catalyst, since this may give an undesirable increase in hydrocracking in this zone or zones. Mixtures, having acidic properties, of alumina with at least one other oxide of elements from Groups III and IV of the Periodic Table may also be employed as the catalyst support, for example, mixtures with boria, silica, titania, or zirconia. The oxide or oxides other than alumina are preferably present in amount of from 1 to 25% Wt., by weight of the total (second) catalyst.

The platinum group metal content and methods of adding it to the support may be the same as for the low acidity catalyst.

As stated earlier, the feedstock is first contacted with the catalyst having the low acidity support, and then with the second catalyst. It is desirable that no separation of any part of the reaction mixture takes place between contacting the two catalysts. Preferably the pre sure and gas flow rate are constant for both catalysts.

The amount of low-acidity catalyst to total catalyst may conveniently be in the range 5 to vol., more particularly -15 to 75% vol. Since in commercial practice reformers have a number of separate reactors in series, for Example 3, the first reactor, and also, if desired, the second reactor can be used for the low-acidity catalyst and the other reactor or reactors for the more acidic catalyst.

The reforming conditions under which the low-acidity catalyst is used may be selected from the following When the process uses both low-acidity and high-acidity catalysts, the process conditions for the acidic catalysts are also selected from the same ranges.

The invention is illustrated by the following examples.

EXAMPLE 1 This example, and Example 2 illustrate the preparation of a low acidity alumina-based catalyst and compare results obtained by its use in accordance with one embodiment of the invention with those obtained by the use, separately, of high acidity alumina-based catalysts.

Catalyst 1.Pseud0b0ehmire-derived low acidity alumina 2000 g. of powdered aluminium isopropoxide were slurried into 8 litres of 6 percent weight hydrogen peroxide solution, and stirring continued for 6 days. The slurry was then centrifuged, washed with deionized Water to remove most of the hydrogen peroxide, and reslurried in 1 liter of deionized water. 150 ml. of solution containing 7.5 g. of of chloroplatinic acid (platinum content about 40 percent weight) were added slowly to the slurry which was vigorously stirred for about 30 minutes. Hydrogen sulphide gas was then bubbled through the slurry for about 1 hour, after which it was centrifuged and washed with about 3 liters of acetone to remove some of the residual water from the filter cake. The partially dried filter cake was then left under vacuum overnight, and finally dried in a forced air oven at C.

The dried hydrate was crushed, pelleted to x and granulated to 8-16 mesh. It was then calcined in a muffle furnace for 2 hours at 500 C., cooled in a desiccator and stored in a sealed container until required for use.

Catalysts 1, 2 and 3 were tested for reforming activity under the following conditions.

Plant pressure, p.s.i.g. 450. Catalyst 2.Bayerite-derived high acidity alumina Space velocity, .v./v./hr 2.0.

5 Recycle gas rate, s.c.f./b. 20,000. 2000 g. of aluminium isoproxide were dissolved in 12 g i g teimpemmre 328 liters of Analar benzene, 6 liters of 5 percent weight amam yst c arge m 1 monium hydroxide were added and the mixture stirred Feedstock Z vigorously for 1 hour. After this time hydrolysis of the T f aluminium isoproxide was complete. The benzene layer, Olme racnon containing most of the isopropyl alcohol formed during The catalysts were reduced at 900 F. with dry hydrothe reaction, was decanted, and a further 4 liters of 5 pergen for 2 hours before the unit was brought on stream. cent weight ammonium hydroxide added to the alumina Test periods were carried out at temperatures of 930 hydrogel slurry. Stirring was continued. overnight, after F., 960 F., 975 F. and again at 930 P. which the slurry was centrifuged, washed with about 8 The total on stream time of the test was 110 hours. liters of deionized water, and the filter cake reslurried The liquid product yields and research octane numbers in 4 liters of deionized water. To homogenize the slurry (clear) of the products are given in Table 2 below.

TABLE 2 930 F. 960 F. 975 F. 930 F.

Catalyst Yield, RON Yield, RON Yield, RON Yield, RON percent wt. percent Wt. percent wt. percent wt.

91.6 70.2 81.9 87.7 78. 6 90.1 90. 4 71.9 76.3 84. 7 66. 0 95. 3 62.5 98.6 76. 5 so. 4 75. 9 88.0 65. 9 94. 5 a5. 6 97.7 79. 2 s4. 2

RON =Product octane number, research clear, c0

it was passed six times through a colloid mill (using Car-borundum stones), the clearance being progressively reduced to 0.001 inch. 1500 ml. of 0.880% ammonia were then added to the thickened slurry with vigorous stirring. The slurry was aged at ambient temperature in a sealed polythene container.

After 10 days ageing, the slurry was centrifuged washed to remove most of the ammonium hydroxide, and the filter cake reslurried in deionized water. 150 ml. of solu tion containing 8 g. of chloroplatinic acid (platinum content about percent weight) were added slowly, with vigorous stirring, to the alumina hydrogel slurry. After 30 minutes stirring, hydrogen sulphide gas was bubbled through the slurry for hour, and then the platinumalumina hydrogel was dried in a forced air oven at 120 C.

The platinum-alumina hydrate was pelleted, granulated and calcined in the same way as Catalyst 1.

A further catalyst, Catalyst 3, which was used for comrrected to 05+ stabilized basis.

lationship obtained with Catalyst 1. At RON, for

example, the yield advantage is 5% wt. and at 78% wt. yield the octane number advantage is 5 numbers.

(b) EXIT STABILIZER GAS MAKES At any given octane number, the exit gas make and the hydrogen content of that gas were highest for Catalyst 1 and lowest for Catalyst 2. At 90 RON for example the hydrogen make was parative test was a commercially available platinum-alu- S i/b mina-halogen catalyst. Catalyst 1 700 Chemical and physical data on the three catalysts are Catalyst 2 330 given in Table 1 below. 40 Catalyst 3 490 TABLE 1 Catalyst 1 2 3 Composition;

Psendoboehmite Eta-alumina of small crystalline size.

Pt-Alumina (after calcination for 2 hr. at 1,020" F.).

Benzene Cllenlisorption Data:

Benzene/Pt atom ratio 1 Benzene adsorption on alumina Mainly bayerite with a little norstrandite and pseudoboehmite.

Eta-alumina 2 Reversible benzene chemisorption at 103 C. on the alumina base.

9 The stabilizer gas make showed the reverse trend, the figures at 90 RON being S.c.f./b. Catalyst 1 300 Catalyst 2 470 Catalyst 3 380 These results can be interpreted as showing that Catalyst 1 has a low activity for hydrocracking (a hydrogenconsuming and gaseous hydrocarbon-producing reaction) and a good activity for dehydrocyclization and dehydrogenation (hydrogen-producing reactions).

EXAMPLE 2 The pseudo-boehmite based platinum-alumina (Catalyst l) was tested for reforming activity under more severe operating conditions to produce C reformate of 95 and 100 RON (clear).

The following operating conditions were employed:

The catalyst was reduced at 900 F. with dry hydrogen for 2 hours before the unit was brought on stream.

The following results were obtained:

10 The run was voluntarily terminated at 1,011 HOS (7.8 bbL/lb.)

Despite the very severe operating conditions, the run was characterized by the very high stability of operation. No noticeable activity decline was observed while processing at either 95 or 100 octane number level.

EXAMPLE 3 This example gives results obtained by the use in combination of a low acidity alumina based catalyst together with a high acidity alumina based catalyst, according to the second embodiment of the invention.

The two catalysts were Catalyst 1, prepared as described in Example 1, and with the physical and chemical data given in Table 1, and a commercial reforming catalyst consisting of 0.58% wt. platinum and 0.8% wt. chlorine on an acidic alumina having a reversible benzene chemisorption of 17 ,umols/ g.

Four combinations were examined, viz.:

Case A Commercial catalyst only.

Case B 20% catalyst 1+80% commercial catalyst.

Case C 60% catalyst 1+40% commercial catalyst.

Case D Catalyst 1 only.

For Case B, as an example, the two catalysts were placed in the reactor, the first (Catalyst 1) at the top of the bed and the second below it, and a downfiow feed system was used. An activity test was carried out at a series of temperatures and under the following operating conditions:

(a) OPERATION AT 95 OCTANE NUMBER LEVEL Temperature 930, 960, 900 F.

Pressure 450 p.s.i.g. Hours on stream 214-220 405-411 Space velocity (on total catalyst) 2.0 v./v./hr.

Gas flow rate 20,000 s.c.f./b. RON (Clear) 94.6 94.7 Feedstock Dry desulphurized Liquid yield, percent wt 77. 4 77. 6 90 140o C Exit gas, s.c.f./b 910 899 H2 content, percent..- 75 73. 5 ASTM llght Stabilizer gas. s.c.f./b 262 270 gasoline (b) OPERATION AT 100 OCTANE NUMBER LEVEL Hours on stream 594575 37-343 1 000-13 Th6 Same 9peljatmg Procedure Was applled 23 the catalyst combinatlon of Case A and of Case C, the results RON (Clear) 997 998 993 being summarized in Table 3. Table 3 also shows the gq nd yield, p r ent wt- 65 63- 3 63- results obtained with Case D. In this instance the condib;, gfi[: I: 64-0 645 63,8 tions are similar to those for Cases A to C, except that Stabilizer gas, s.c.f. 428 428 417 the mid-bed temperatures are higher in order to bring the product octane numbers up to the required level.

TABLE 3 Catalyst Case A Case 13 Case C Case D Test Period Number l 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 Catalyst mid-bed temperature, F 930 959 901 943 930 959 900 929 931 900 900 930 959 984 1010 960 Stabilized Reformate Product:

Research Octane Number, Clear 95.8 101.4 86.4 97.8 96.6 102.3 86.4 95.9 92.0 99.1 80.5 91.3 92.1 95.6 98.9 90.0 Reformate yield, percent wt 73.7 69.4 82.9 72.0 75.4 69.4 84.5 75.3 80.5 75.5 88.4 80.7 84.0 78.1 73.5 84.2 Available Hgproduetion, s.c.f./b 672 743 572 660 693 772 615 689 732 758 610 730 689 761 738 694 Hz content ofreeycle gas, percent mol 66.2 62.9 77.6 66.3 72.9 65.9 79.2 72.5 78.5 72.5 83.5 80.5 76.0 73.0 67.1 78.3

Referring now to the accompanying drawings, the research octane number, clear, is plotted against the C 4- liquid product yield for Cases A to D in FIG. 4, the research octane number, clear against the stabilizer gas make in FIG. 5a and the available hydrogen production in FIG. 5b.

Table 4 below compares Cases B, C, and D with Case A, and gives, in addition to the yield advantage at given octane numbers, the temperature penalty at these octane numbers.

It will be seen from FIG. 4 and Table 4 that Case B gives approximately a 1.5% yield advantage over Case A at all octane numbers with no temperature penalty. If a temperature penalty of 15-20 F. is acceptable, then Case C provides a yield advantage over Case A that increases with increasing octane number. Case D has a yield advantage over Case A at all octane numbers at least up to 100, but the temperature penalty is higher.

'FIGURE 5a shows that each of Cases B to D produced more hydrogen at a given octane number than Case A, and in conjunction with the stabilizer gas production, indicated in FIGURE 5b this can be considered to show that each of the combined catalysts has a higher dehydrocyclization/ dehydrogenation activity and a lower hydrocracking activity than the known high acidity catalyst when used alone.

TABLE 4.-COMPARISON OF CASES B, C AND D WITH CASE A RON Clear 90 95 100 Reiormate Yield Advantage over Case A, percent wt.:

I claim:

1. A process for the catalytic reforming of hydrocarbons which comprises contacting a C 204 C. hydrocarbon fraction, in the presence of a hydrogen-rich gas, with a catalyst comprising platinum on a support consisting of an alumina having a reversible benzene chemisorption of up to 5 umols/g, at a temperature of from 8001100 F, a pressure of from -1000 p.s.i.g., a space velocity of from 0.01-10 v./v./hr., and a gas flow rate of up to 20,000 s.c.f./b.

2. A process as claimed in claim 1, wherein the catalyst support consists of an alumina having a reversible benzene chemisorption of from 0.3- mols/g.

3. A process as claimed in claim 1, wherein the temperature is 900-1050 F., the pressure is 200-500 p.s.i.g., the space velocity is 1-5 v./v./hr., and the gas flow rate is 200020,000 s.c.f./b.

4. A process as claimed in claim 1, wherein the said alumina is derived from a pseudoboehrnite alumina hydrate precursor obtained by hydrolysis of an aluminium alcoholate at a temperature of less than 70 C.

5. A process as claimed in claim 1, wherein the platinum content of the catalyst is 0.0 l5% weight.

6. A process for the catalytic reforming of hydrocarbons, which comprises contacting a C 204 C. hydrocarbon frac-tion, in the presence of a hydrogen-rich gas with a first catalyst comprising platinum on a support consisting of an alumina having a reversible benzene chemisorption of up to 5 mols/g, and then with a second catalyst comprising platinum on a support consisting of an alumina having a reversible benzene chemisorption of at least ,umols/g, at a temperature of from 800- 1100 F., a pressure of from 0-1000 p.s.i.g., a space veloc- 12 ity of from 0.01-10 v./v./hr., and a gas flow rate of up to 20,000 s.c.f./b.

7. A process as claimed in claim 6, wherein the support of the said first catalyst consists of an alumina having a reversible benzene chemisorption of from 03-5 nmols/ g.

8. A process as claimed in claim 6, wherein said first catalyst constitutes from 15-75 vol. of the total volume of the first and second catalysts.

9. A process as claimed in claim 6, wherein the temperature is 900-l050 F., the pressure is 200-500 p.s.i.g., the space velocity is l-5 v./v./hr., and the gas flow rate is 2000-20,000 s.c.f./b.

10. A process as claimed in claim 6, wherein the alumina support of the said first catalyst is derived from a pseudoboehmite alumina hydrate precursor obtained by hydrolysis of an aluminium alcoholate, at a temperature of less than 70 C., and wherein the alumina support of the said second catalyst is derived from a precursor consisting predominantly of beta-alumina trihydrate also known as bayerite.

11. A process as claimed in claim 6, wherein the total platinum content of the first and second catalysts is 0.01- 5% weight.

12. A process for the catalytic reforming of hydrocarbons, which comprises contacting a C -204 C. hydrocarbon fraction, in the presence of a hydrogen-rich gas, with a first catalyst comprising platinum on a support consisting of an alumina having a reversible benzene chemisorption of up to 5 mols/g, and then with a second catalyst comprising platinum on a support consisting of a mixture of alumina with at least one other oxide of elements selected from Groups III and IV of the Periodic Table, said second catalyst being more acidic than said first catalyst, at a temperature of from 8001100 F., a pressure of from 0-1000 p.s.i.g., a space velocity of from 0.01-10 v./v./hr., and a gas fiow rate of up to 20,000 s.c.f./b.

13. A process as claimed in claim 12, wherein the support of the said first catalyst consists of an alumina having a reversible benzene chemisorption of from 03-5 mols/ g.

14. A process as claimed in claim 12, wherein the support of the said second catalyst comprises from 1-25% weight, by weight of said other oxides.

15. A process as claimed in claim 12, wherein said first catalyst constitutes from 15-70% vol., of the total volume of the first and second catalysts.

16. A process for the catalytic reforming of hydrocarbons, which comprises contacting a C 204 C. hydrocarbon fraction, in the presence of a hydrogen-rich gas, with a first catalyst comprising platinum on a support consisting of an alumina having a reversible benzene chemisorption of up to 5 nmols/g, and then with a second catalyst comprising platinum on a support consisting of alumina and from 0.18% weight of halogen by weight of the said second catalyst, said second catalyst being more acidic than said first catalyst, at a temperature of from 800-1100 F., a pressure of from 0-1000 p.s.i.g., a space velocity of from 0.0-l0 v./v./hr., and a gas flow rate of up to 20,000 s.c. ./:b.

17. A process as claimed in claim 15, wherein the support of the said first catalyst consists of an alumina having a reversible benzene chemisorption of from 0.3-5 rnols/ g.

18. A process as claimed in claim 15, wherein said first catalyst constitutes from 15-75% vol. of the total volume of the first and second catalysts.

19. A process for the catalytic reforming of hydrocarbons, which comprises contacting a C -204" C. hydrocarbon fraction, in the presence of a hydrogen-rich gas, with a first catalyst comprising platinum on a support consisting of an alumina having a reversible benzene chemisorption of from 0.3-5 mols/g, and then with a second catalyst comprising platinum on a support consisting of- 1050 F., a pressure of from 200-500 p.s.i.g., a space ve- References Cited locity of from 1-5 v./v./hr., and a gas flow rate of from UNITED STATES PATENTS 2000-20,000 s.c.f./b., said first catalyst constituting from 1575% vol. of the total volume of the first and second 6/1957 K1mbe1,hn et a1 208138 catalysts, the total platinum content of the first and second 5 5/1959 Hfimmmger et a1 208*65 2,903,413 9/1959 Kirshenbaum et a1. 208-38 catalysts being 0.01 5% wel ht, the alumlna support of 2 h the first catalyst being derived from a pseudoboehmite 2 ii lg g f alumina hydrate precursor obtained by hydrolysis of an aluminium alcoholate at a temperature of less than 70 C., 4 and the alumina support of the second catalyst being de- 10 DELBDRT GANTZ Pnmmy Emmmer' rived from a precursor consisting predominantly of beta- H. LEVIN Assistant Examineralumina trihydrate also known as bayerite.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,328,286 June 27, 1967 Paul Anthony Lawrance It is hereby certified that error appears in the above numbered ent requiring correction and that the said Letters Patent should read as corrected below pat- In the heading to the printed specification, line 6, for "The British Petroleum Company" read The British Petroleum Company Limited column 7, line 47, after "centrifuged" insert a comma; columns 9 and 10, TABLE 3, seventeenth column, line 1, for "90.0" read 90.6 column 12, line 46 for "15-70%" read 15-75% Signed and sealed this 29th day of October 1968.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

6. A PROCESS FOR THE CATALYTIC REFORMING OF HYDROCARBONS, WHICH COMPRISES CONTACTING A C5-204*F. HYDROCARBON FRACTION, IN THE PRESENCE OF A HYDROGEN-RICH GAS WITH A FIRST CATALYST COMPRISING PLATINUM ON A SUPPORT CONSISTING OF AN ALUMINA HAVING A REVERSIBLE BENZENE CHEMISORPTION OF UP TO 5 UMOLS/G., AND THEN WITH A SECONE CATALYST COMPRISING PLATINUM ON A SUPPORT CONSISTING OF AN ALUMINA HAVING A REVERSIBLE BENZENE CHEMISORPTION 